Hiroyuki Hirashima

Nonuniform Distribution of Tundra Snow Cover in Eastern Siberia

Abstract Characteristics of snow cover in a small watershed in Arctic tundra near Tiksi, eastern Siberia, were studied by observation and model simulation. First, helicopter observation, snow survey on three traverse lines, and trigonometric survey of snowdrift were carried out at the end of the winters of 1999 and 2000 to estimate the amount and distribution of snow. The observed locations of snowdrifts in the two years were mostly the same. The area of the snowdrift, including shallow snowdrifts, was larger in the year of high winter precipitation than in the year of low winter precipitation. The snowdrifts were formed on the riverbed and lee sides of cols rather than on steep leeward-facing slopes. Second, snow distribution was simulated using a snow distribution model. The results of simulated snow distribution at the end of winter agreed well with the results of the observations. The results of the simulations showed that approximately 40% of winter precipitation was sublimated. The simulations also ...

Investigation of the sorption of Zn(II) on surface soils using a radiotracer technique

Abstract Radiometric sorption experiments were carried out on surface soil samples collected from several sites around Sapporo city (Hokkaido, Japan) in order to evaluate their capacities for the sorption of Zn(II). The maximum sorption (Am) of Zn(II), obtained from the sorption isotherm, was only 2–5% of the cation exchange capacity (CEC). The Am values were correlated with the pH of the soil suspensions, which indicates that zinc sorption would occur competitively with protons in the suspension. The effect of organic matter on the Zn(II) uptake was estimated from the Am change of the individual samples before and after heat treatment. Coordinate uptake of the Zn(II) into the degrading organic matrices was believed not to be important for Zn(II) sorption in some of the present soil samples.